For many years agricultural balers have been used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. Usually, a mower-conditioner cuts and conditions the crop material for windrow drying in the sun. When the cut crop material is properly dried, a round baler is pulled along the windrows to pick up the crop material and form it into cylindrically shaped round bales. More specifically, the pickup of the baler gathers the cut and windrowed crop material from the ground and then conveys the cut crop material with a conveyor, such as a rotating conveying rotor, into a bale-forming chamber within the baler. The pickup assembly has a drive mechanism that operates to activate both the pickup and the conveying rotor, and the pickup drive mechanism is operably connected to and driven by the main drive mechanism of the baler. The baling chamber consists of a pair of opposing sidewalls with a series of belts that rotate and compress the crop material into a cylindrical shape. When the bale has achieved a desired size and density, the round baler wraps the bale with twine or other wrapping material, such as film or net, to ensure that the bale maintains its shape and density. Then the operator raises the tailgate of the baler and ejects the bale onto the ground. The tailgate is then closed and the cycle repeated as necessary and desired to manage the field of cut crop material.
The rotor conveyor mechanism (“rotor” or “rotor mechanism”) between the pickup and the bale-forming chamber is usually referred to as the “stuffer”, because it stuffs the crop material into the gap between the floor roll and the starter roll into the bale-forming chamber.
Opening and closing of the tailgate has been controlled by a flow valve, which was located between a source of pressurized hydraulic fluid and an actuator. The position of the flow valve was controlled by a hydraulic lever. To increase efficiency, the rate of opening and closing of the tailgate should be rapid. However, such rapid movement of the tailgate can lead to damage to the baler. Therefore, to slow the rate of opening and closing near the end of the opening or closing portion of the cycle, the hydraulic valve has been “feathered” by positioning the hydraulic lever between its fully open position and its fully closed position. This solution depends on the skill of the operator and requires the attention of the operator.
Exemplary prior art tailgate opening and closing mechanisms, which do not vary the speed of opening or closing, are shown in Viesselmann et al. U.S. Pat. No. 5,622,104 and Anderson U.S. Pat. No. 6,272,825. Biziorek et al. U.S. Patent Application Publication No. 2005/0247215 discloses a round baler that varies the speed of the opening and closing of the tailgate using tailgate position sensors.
In order to prevent rapid decelerations of the tailgate when it meets its closing stops, the Viesselmann system includes an orifice that continuously slows the flow of oil to and from the tailgate hydraulic actuators to effectively cushion the closing of the tailgate. The flow restriction valve assembly of Anderson is either open or closed and prevents the tailgate from slamming shut. The result is that the tailgate motion is slowed and the open and close cycle time of the tailgate is increased, making the baling operation less efficient.
To improve efficiency, it is desirable to restrict flow of the fluid to the actuator only near the end of the opening and closing motions. While the flow of hydraulic fluid to the tailgate actuator of Biziorek is regulated by valve device, the control system of Biziorek requires a number of positional sensors to determine the position of the tailgate. The addition of the positional sensors increases the cost of the baler due to increased installation cost, as well as the addition of components that are subject to failure. Additionally, an important functional limitation of Biziorek is the valve in the fluid circuit that forcibly causes the hydraulic system to change speed when either in a closed or open state.
The embodiments provided herein provide for an improved baler by providing faster and smoother tailgate operation and providing less stress on the tailgate that is involved in ejecting the bale with efficient operation and advantages over prior controllers of tailgate operation. Rather than forcibly causing the tailgate to close by opening and shutting of a single valve, some embodiments accomplish a smoother opening and closing function the tailgate by utilization of the combination of one or more check valves and a restrictive orifice which cause back pressure in the circuit. Float of the tailgate is accomplished while the tailgate is in a substantially open positions and while the circuit is in one or more of the hydraulic states described herein.